How much will your insulation cost? The price of installing insulation in your home or building are relatively easy to calculate once you have a few measurements and, not only will this help you budget and compare prices, it gives you a great way to work out how much you will save on your heating and energy bills after installing the insulation. The various insulation prices I have included on this page are the averages from a couple of major online suppliers together with the government-recommended thickness of insulation.

Insulation prices

I have put together a simple DIY insulation calculator to help you work out the cost of insulating a standard three-bedroom house with an attic space of 44square metres. If you are installing standard rolls of insulating material, you should install to a recommended thickness of 270mm.

A roll of top-up 170mm thick glass mineral wool costs $25 (in the UK it’s much cheaper at £3 per roll  since it includes Carbon Emissions Target savings). Each roll is 1.11m wide and 4.9m long.

A roll of basic 100mm thick glass mineral wool costs $40 (in the UK it’s much cheaper at £16 per roll  since it includes Carbon Emissions Target savings). Each roll is 1.2m wide and 12m long.

Note that the standard gap between joists is either 60 or 40cm wide, and the rolls of insulation normally have perforations to help you tear the roll and fit between these joist widths.

 As a comparison, for more expensive sheeps-wool based insulation rolls, which are normally pre-cut to 37cm to fit between the more common 40cm joist-widths, a roll is $25 / £15 and 3m long.
Caution! If you’re installing glass mineral wool, make sure you wear gloves, a breathing mask and full-length sleeves and trousers to avoid any skin contact with the wool – which will irritate your skin. An alternative is to buy encased insulation (the glass mineral wool is safely encased in plastic sheets. The average price for this type of insulation is just a few dollars more per roll.